Pentagon Bulks Up 'Bunker Buster' Bomb to Combat Iran

WASHINGTON—The Pentagon has redesigned its biggest "bunker buster" bomb with more advanced features intended to enable it to destroy Iran's most heavily fortified and defended nuclear site.

U.S. officials see development of the weapon as critical to convincing Israel that the U.S. has the ability to prevent Iran from getting a nuclear bomb if diplomacy fails, and also that Israel's military can't do that on its own.